This application claims foreign priority benefits under 35 U.S.C. xc2xa7 119 of German application DE 10144326.9 filed Sep. 10, 2001.
The invention relates to a method and a system for monitoring a tire air pressure.
The air pressure in a tire is typically subjected to specific changes. These changes in the tire air pressure can be caused, for example, by various parameters such as the ambient air pressure around the tire. Likewise, the air pressure in a tire changes depending on whether the tire is used in warmer or colder areas.
U.S. Pat. No. 5,895,846 discloses a method of processing signals in a system for monitoring tires on a vehicle during its operation. In this case, only the tire pressure and the internal temperature of the tire but no further parameters that determine the air pressure in a tire are taken into account, so that a defect in the tire may mistakenly be detected.
The object of the invention is to provide a method and system for monitoring a tire air pressure, it being possible to determine reliably whether there is an optimum tire pressure in spite of the effect of various factors which determine the tire air pressure.
This object may be achieved by a method of monitoring a tire pressure, in which one or more parameters that influence the tire pressure are measured, and an optimum tire pressure is calculated, based on the measured parameter or parameters. In addition, a measured tire pressure may be compared with the optimum tire pressure, in order to generate a deviation signal in the event of a predetermined deviation. The predetermined deviation may be defined, for instance, by upper and lower limits. When the deviation signal exceeds the upper limit or falls below the lower limit, a deviation value may be increased. When no deviation signal is present the deviation value may be reduced. An alarm signal may be generated when the deviation value reaches a predetermined threshold value.
An example embodiment of a system for monitoring a tire pressure may include at least one tire to be monitored, as well as at least one sensor for measuring at least one parameter that influences the air pressure of the tire. The embodiment may also include an air pressure sensor for measuring a current tire air pressure, and an evaluation unit, which receives the parameter measured by the sensor and measured data from the air pressure sensor. The evaluation unit calculates an optimum tire pressure on the basis of the at least one measured parameter and compares the measured tire pressure with the optimum tire pressure in order to generate a deviation signal in the event of a predetermined deviation. The predetermined deviation is defined by an upper and lower limit. When the deviation signal generated exceeds the upper limit or falls below the lower limit, a deviation value is increased. The deviation value is reduced when no deviation signal is present. An alarm signal is generated when the deviation value reaches a predetermined threshold value.
Other advantageous developments of the invention may be appreciated upon a comprehensive review of this disclosure, including sections such as the Detailed Description and the Claims.
The influence of various parameters that influence the tire air pressure can be taken into account reliably during the monitoring of the air pressure in the tire.
In this case, a tolerance band is defined, within which a currently measured tire air pressure may deviate from an optimum tire air pressure without an alarm signal being generated.
According to one or more embodiments, it is possible to adapt the method to various vehicle types easily, since a vehicle-specific tire pressure, for example one specified by the vehicle manufacturer, is taken into account in monitoring the tire pressure.
According to one or more embodiments, various parameters that determine the tire air pressure are taken into account in monitoring an optimum tire air pressure. In this way, the optimum tire air pressure can be calculated at any time, even when external conditions change.
According to one or more embodiments, the tolerance band can be variable, by which means it can be adapted to various parameters that influence the tire air pressure. Thus, by using the method according to the invention, for example secure detection of a tire fault can be carried out, external influences being taken into account.
According to one or more embodiments, the driver of a vehicle which contains at least one tire whose tire air pressure is to be monitored is informed, for example, about a pressure drop in the monitored tire. This is done, for example, at a gas station, where there is the possibility for the driver to refill the tire with air.
According to one or more embodiments, the driver is informed about the still permissible loading of the vehicle. This can be carried out continuously or only when a permissible loading limit is exceeded.